Tag: low-cost

Are Low-Cost Sensors Random Number Generators?

Sotirios Papathanasiou5 Comments

Low-cost sensors aka LCS are commonly used in an effort to measure air pollutants like particulate matter all around the world, indoors and outdoors. Their low price has driven a lot of interest from many communities. Academics, experts, and consumers have embraced them because they are cheap to get and easy to embed in an IoT solution.

Countless air quality monitors use low-cost sensors (mostly from China) and although they are great as educational tools, their low accuracy leads to wrong conclusions most of the time.

Wrong conclusions are as bad as misinformation or fake news. Air pollution doesn’t kill instantly (most of the time) and it doesn’t create severe health issues in the short-term, but after an extended period or at least when we notice the consequences. One exception is carbon monoxide (CO) as it can kill people instantly and this is the reason we don’t see many low-cost CO sensors. There are some regulations that protect the consumers. Moreover, companies don’t want to take responsibility by using a low-cost CO sensor because they can get sued easily by the family of a victim when the air quality monitor won’t notice the increase of the gas indoors. Liability!

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MasterClass: Air Quality Data Visualization with R Studio & Packages

Sotirios Papathanasiou6 Comments

R Studio and its packages are used by hundreds of thousands of people to make millions of plots. I use it to compare air sensor data from different air quality monitors/sensors or to visualize air pollution levels.

In this article we will explore both how we can visualize air quality data from publicly available sources and how you can create statistical correlations between different pollutants or different sensors to find the correlation coefficient or correlation of determination.

First: Get the Right Packages

Packages are collections of functions, data, and compiled code in a well-defined format, created to add specific functionality. Here are some of the packages that we will install inside RStudio and use.

#You can either get ggplot2 by installing the whole tidyverse library
install.packages(tidyverse)

#Alternatively, install just ggplot2
install.packages(ggplot2)

#saqgetr is a package to import European air quality monitoring data in a fast and easy way
install.packages(saqgetr)

#worldmet provides an easy way to access data from the NOAA Integrated Surface Database
install.packages(worldmet)

#Date-time data can be frustrating to work with in R and lubridate can help us fix possible issues
install.packages(lubridate)

#Openair is a package developed for the purpose of analysing air quality data
linstall.packages(openair)
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OPEN Ambient Air Quality DATA

Sotirios Papathanasiou5 Comments

There is some serious competition in the market of environmental monitoring and particularly in air quality. There are a lot of ambient air quality monitors available with great features and great sensors, the problem is that society doesn’t benefit from the variability of monitors because AQ data are scattered in different platforms/maps. It is hard for end-users and citizens to find which monitor is active and where (especially if you move). Someone needs to gather low-cost AQ data from everywhere and offer it to users in easy service.

Last year, on my trip across Europe, I monitored air quality with a portable monitor, but I wanted to compare the data I got against the official or other low-cost monitors out there. It was impossible!

The openaq team is doing just that. They are gathering data from official and low-cost sensors (stationary and mobile). Unfortunately, even today I cannot access data from specific low-cost monitors that take advantage of the API and their open map.

This are the brands that collaborate and they provide data to openaq:

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High-End Professional vs Low-Cost Professional Ambient Air Quality Monitors

Sotirios Papathanasiou4 Comments

In the space of ambient air quality monitoring, there are two basic and distinctive categories of professional air quality monitors; the High-End Professional and Low-Cost Professional monitors. I have been asked multiple times to recommend monitors for scientific studies and the deployment of them in cities.

It is very important to understand the strengths and weaknesses of both categories. It is also mandatory to recognize the fact that we will never get the exact same measurement from either category of sensors.

High-End Professional AQA

High-End Professional ambient air quality analyzers are used mostly by governments inside the air quality stations we have in most cities. Their strength is that they meet international standards for accuracy and they are certified by the EU (and similar bodies) to meet minimum performance requirements, in order to ensure that the measurement methods comply with the Data Quality Objectives set down in the Ambient Air Quality Directive (2008/50/EC) and in the amending Directive (EU) 2015/1480. Their weakness is that they require lots of energy to operate. In most cases, they are inside a fixed container with a refrigeration system to keep conditions stable. They are big and boxy in size and very expensive to purchase and operate. Additionally, they need constant maintenance by a technician. Another weakness is that in most cases these analyzers are not smart enough to broadcast measurement in real-time to the Cloud and they require other pieces of equipment to do that job, as a result, the cost of operation increases.

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